Dergi makalesi Açık Erişim

Investigating the role of strangeness in baryon–antibaryon annihilation at the LHC

2023    CERN İşbirliği

Annihilation dynamics plays a fundamental role in the baryon–antibaryon interaction ($\mathrm{B–}\stackrel{‾}{B}$) at low-energy and its strength and range are crucial in the assessment of possible baryonic bound states. Experimental data on annihilation cross sections are available for the $\mathrm{p–}\stackrel{‾}{p}$ system but not in the low relative momentum region. Data regarding the $\mathrm{B–}\stackrel{‾}{B}$ interaction with strange degrees of freedom are extremely scarce, hence the modeling of the annihilation contributions is mainly based on nucleon–antinucleon ($\mathrm{N–}\stackrel{‾}{N}$) results, when available. In this letter we present a measurement of the $\mathrm{p–}\stackrel{‾}{p}$, $\mathrm{p–}\stackrel{‾}{\Lambda }\oplus \stackrel{‾}{p}\text{–}\Lambda $ and $\Lambda \text{–}\stackrel{‾}{\Lambda }$ interaction using correlation functions in the relative momentum space in high-multiplicity triggered pp collisions at $\sqrt{s}\phantom{\rule{0.25em}{0ex}}=\phantom{\rule{0.25em}{0ex}}13$ TeV recorded by ALICE at the LHC. In the $\mathrm{p–}\stackrel{‾}{p}$ system the couplings to the mesonic channels in different partial waves are extracted by adopting a coupled-channel approach with recent χEFT potentials. The inclusion of these inelastic channels provides good agreement with the data, showing a significant presence of the annihilation term down to zero momentum. Predictions obtained using the Lednický–Lyuboshits formula and scattering parameters obtained from heavy-ion collisions, hence mainly sensitive to elastic processes, are compared with the experimental $\mathrm{p–}\stackrel{‾}{\Lambda }\oplus \stackrel{‾}{p}\text{–}\Lambda $ and $\Lambda \text{–}\stackrel{‾}{\Lambda }$ correlations. The model describes the $\Lambda \text{–}\stackrel{‾}{\Lambda }$ data and underestimates the $\mathrm{p–}\stackrel{‾}{\Lambda }\oplus \stackrel{‾}{p}\text{–}\Lambda $ data in the region of momenta below 200 MeV/c. The observed deviation indicates a different contribution of annihilation channels to the two systems containing strange hadrons.